Air conditioner repair

Why does my AC Unit make noise?

AC unit noise starts to worry many happy owners of such climatic equipment, especially after several years of its use. A working AC unit should produce only homogeneous monotonous noise. Depending on the quality of a particular model, AC unit noise may be slightly more or less noticeable to others. At the hearing, this is perceived as a whisper, to which a person subsequently does not pay attention. It is rather difficult to answer this question since there are a great many causes of noise. There is only one thing to say for sure: this problem must be solved without delay in order to prevent serious damage and failure of the unit.


Non-standard AC unit noises


AC unit, in principle, can not be completely silent, as marketers promise. Inside there are many moving parts (bearings, motors, and turning mechanisms) that make noise, and they are almost impossible to disguise with housing or sound filters.

And although the majority of non-periodic intermittent sounds do not speak about anything good, yet some of them are completely safe and can be eliminated on their own.




  • The ac unit makes noise after turning off.


The main reason for the ac unit noise, in this case, is the airing of the highway with freon. This may occur due to poor installation of the system when a specialist has not spent the entire amount of work. In particular, most likely the evacuation was not performed, the freon was refilled, and the freon track was poorly mounted. The reason is the insufficient length of the tubes or the formation of strong bends that prevent the liquid from moving. Then air traffic jams are formed in the track, and when freon breaks through them, noise occurs. Depressurization can also occur over time.

It is extremely not recommended to flush the tube by yourself and add liquid. To do this, you need special equipment and experience in conducting such operations.


  • Air conditioning rustles with the wind.


If the noise is distributed only during the wind, this means that the air directed from the street comes through the pipes to the bath with condensate. In this case, the unit has a noise similar to the gurgling of water in a glass, when the air is blown into it with the help of a straw.

To fix this, it is enough to bend the external drainage hose (it goes outside) so that the wind stops blowing into the unit system. Another option is to additionally install a siphon for the AC unit, which will drain excess liquid into the sewer system. Then the noise during the wind is almost completely eliminated.

Another reason is the strong bending of the drainage tube between the outer and inner blocks. Water accumulates in the folds, and when the wind blows from the street, this very noise arises.

ac unit noise


  • Noise during operation of the ac unit

Sometimes the AC unit during operation for some reason buzzes periodically. This applies to the outdoor unit (located on the street) and the internal (located in the room).

Noise can produce a self-cleaning system that is turned off. This sound is the norm.

Occasionally a program crash occurs that controls the interaction of the split-system units. Then one of the blocks may suddenly start working in the off state. In this case, the ac unit needs to be reprogrammed so that the indoor unit can again successfully synchronize with the external one.

However, the most common causes of hum are severe fan contamination, dust, lint or insect colonies (bees, wasps). In such conditions, the fan blades begin to give a different load on the core during rotation. The result is an imbalance of internal structures, vibration, and the device starts to make a lot of noise.

An AC unit may have a mechanical failure:

  • The bearing was not sufficiently lubricated, and then failed.
  • There is a foreign object or dust inside the mechanism.
  • Buzz when turned on – perhaps the motor is not enough voltage from the mains to start. It is necessary to check the wiring in the room for performance and the presence of bare insulation.
  • Damage or wear to the internal parts of the AC unit (for example, deformation of one of the fan blades or severe compressor wear).




  • Slapping and noise of falling drops


Noise falling drops or liquid popping when turning on the air compressor is unlikely to mean serious damage.

In the first case, condensate forms during the operation of the defrosting mode.

In the second – the sound of the refrigerant flowing to the lowest point of the track.


  • Knock and noise in the off state.


If the body of the AC unit was made of poor quality plastic, sharp, loud noises might appear before and after switching on. This is a reaction to temperature extremes. You can fix it only by buying another model of a split-system AC with a better plastic, where it will not be deformed so much when switching modes.


  • Troubleshooting

To the equipment of the AC unit served as long as possible, it must be cleaned regularly and conduct a technical inspection. The frequency of checks depends on the frequency of use of the AC unit, as well as on the dustiness of the room and the external environment in which the split system is placed.

For an average apartment, it is enough to clean the indoor unit of the AC unit from dust and dirt at least once every couple of weeks. Exterior, needs to clean a couple of times a year. Another signal that it is time to wash the internal parts of the AC unit from dirt – the device has ceased to condition the room fully.


Why do I need to contact the AFR Dynamics service center?



Naturally, it is not recommended to repair the internal parts of the controller itself. The same applies to charge with refrigerant and cleaning the outdoor unit of the split system of the AC unit.


We repeat that if you can not accurately diagnose the source of loud noise in your split system, or are unsure of your abilities, then do not show amateur and contact professionals.

Before starting maintenance or repairing the AC unit, an AFR Dynamics representative will hear the owner’s complaints. Based on them, he will conduct his own diagnostics of the noise. Then the full complex of works will be carried out:

  • Cleaning the air filters of the indoor and outdoor unit
  • Flushing drainage system
  • Evacuation of pipes and refueling of freon
  • Lubrication of parts
  • Minor repairs if required

However, if the AC unit compressor was broken, its repair will most likely exceed the cost of AC unit itself. It is easier to buy a new AC unit. If steel sounds unusual for the AC unit noise, you need to find out the cause as soon as possible. Otherwise, the problem may intensify up to complete breakdown. Prevention requires regular maintenance.